Electric toothbrushes

ABSTRACT

In a first embodiment an electric toothbrush having a housing containing an electric motor, the motor being drivingly connected to a first brush head rotatably mounted on an end of the toothbrush remote from the motor and adjacent to at least one other rotatable brush head. In a second embodiment a packaged electric toothbrush including a “try me” facility for remotely testing the operation of the toothbrush, which “try me” feature comprises a two-sided metal strip such as aluminum foil, separated by a dielectric material, respective sides of the strip being connected at one end to respective parts used to operate the electric toothbrush and the other end of the strip being folded over and including a centrally disposed aperture onto which is a bendable metal connector such that upon bending or pressing of the connector the two sides of the strip are electrically connected together to temporarily operate the toothbrush whilst still in its packaging.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a division of application Ser. No.09/969,632, filed Oct. 4, 2001.

FIELD OF INVENTION

[0002] This invention relates to electric toothbrushes including thosepowered by a rechargeable battery from a mains domestic electricitysupply.

BACKGROUND TO THE INVENTION

[0003] In U.S. Pat. No. 5,226,206, there is described an electrictoothbrush having twin brush heads which are drivingly connectedtogether by a rack and pinion assembly in which the rack is reciprocatedvia a drive shaft connected to a crank shaft mounted at one end forrotation on a gear driven by a motor. The twin brush heads are thereforeable to oscillate about their respective axes either in the samedirection or in opposite directions, depending upon the configuration ofthe rack, this being generally ‘U’ shaped so as to facilitate the use ofgear teeth on the inside thereof for driving the respective heads viarespective pinions in mesh therewith.

[0004] A potential problem with this arrangement is that it isrelatively complex and is not easily cleanable with running water suchthat the moving parts may become clogged with toothpaste or debris. Inaddition, the complexity and number of the parts used to provide theoscillating motion for the twin heads adds to the cost and complexity ofmanufacture.

[0005] In U.S. Pat. No. 5,353,460 the use of a rack and pinion assemblyis dispensed with in favour of a crank mechanism connecting the firstbrush head to the second brush head. The first brush head is directlydriven by a mitre gear or crown wheel which then, in turn, drives thesecond brush head to oscillate in the opposite direction to that of thefirst brush head. This arrangement involves fewer moving parts but stilldepends on the presence of gears and the crank mechanism for itsoperation, leading to the possibility of these moving parts beingdifficult to clean and becoming clogged etc. In addition, because thecrank arm necessarily has to connect the respective brush heads on thesides thereof remote from the bristles, it will be understood thatadditional space is required to provide for free movement of the crankarm when the brush is in use. This also has the disadvantage in that theworking ends of the crank linkage can never be directly exposed torunning water for rinsing and cleaning purposes.

[0006] In a first aspect the present invention is derived from therealization that it would be preferable to have an electric toothbrushhaving multiple, such as two, rotatable brush heads but which dispenseswith the need for gears or crank mechanisms for transferring oscillatingrotary motion from one brush to another, typically a first brush drivenby a connection to an electric motor and the second brush driven bymovement of the first brush.

SUMMARY OF THE INVENTION

[0007] According to a first aspect of the invention there is provided anelectric toothbrush having a housing containing an electric motor, themotor being drivingly connected to a first brush head rotatably mountedon an end of the toothbrush remote from the motor adjacent to at leastone other rotatable brush head, wherein the first brush head includes adrive pin extending therefrom substantially at right angles from theaxis of rotation, the free end of the drive pin being received within aguide slot in a brush head to be driven thereby, the arrangement beingsuch that the drive pin bears against respectively opposite sides of theguide slot to thereby drive a driven brush head clockwise andanti-clockwise about its axis of rotation as the first brush head isalso being oscillated.

[0008] This arrangement has the advantage in that the connection betweentwo or more brush heads is extremely simple and since there are nomoving parts other than the free end of the or each drive pin as itrocks back and forth within the or a respective guide slot, such can beeasily cleaned under running water. A further advantage is that themechanical motion of the brush head driven by the first brush head isnecessarily magnified slightly due to its displacement from the firstbrush head and this overcomes any backlash that may be inherent in thesystem. Although a preferred embodiment of the invention uses only twobrush heads, one driven directly via the drive link between the electricmotor and the brush itself and the other being driven by a drive pinextending from the periphery of the first brush head, nevertheless itwill be apparent that the same principle can be used to drive more thana second brush head and, in turn, the second brush head may itself drivea third brush head, and so on. Additionally, one or more of the brushheads may be of different diameter to the first brush head, although itwill be appreciated that where there are differences in diameter aconsideration of equivalent gear ratios then becomes necessary todetermine whether the difference is too great to allow for the requiredmovement.

[0009] The means by which the first brush head is driven back and forthabout its axis may comprise a bell crank arrangement in which an elbowedend of a crankshaft, drivingly connected at its other end to the motor,is received within an elongated slot extending into the periphery of thefirst brush head diametrically opposite the drive pin (for a twin brushhead toothbrush), the length of the slot being at least as great as therange of movement available to the elbow when the crankshaft is rotatedthrough 360°.

[0010] The use of a drive pin for driving a second brush head has astill further advantage to the linkages referred to in the preamblehereto in that the second head may have a plane of rotation which isangled relative to the plane of rotation of the first brush head, suchas being angled inwardly slightly, although it will be understood thatthere are practical limits to the amount that a second or even more suchbrush heads can be angled with respect to the plane of rotation of thefirst brush head.

[0011] Preferably, the end of the elbowed end of the crankshaft and theor each drive pin is partly spherical and takes the form of a balljoint, each being receivable within a respective slot of substantiallythe same diameter so as to minimize rattle and wear. A convenientarrangement has been found to be a ball joint made of nylon where thebristle holding part of the brush heads are made of e.g. PVC or someother suitable plastics material. Preferably, the slot for receivingeach ball joint is partly arcuate so as to maximize the surface area incontact between the ball joint to thereby decrease the load forces onthe slot and therefore reduce wear.

[0012] According to a second embodiment of the invention, the toothbrushis packaged in e.g. a blister pack and includes a “try me” facility forremotely testing the operation of the toothbrush, such as by aprospective purchaser of the toothbrush, whilst the toothbrush is stillin its protective sales packaging, which “try me” feature comprises atwo-sided metal foil or strip (such as aluminum foil), separated by adi-electric material such as paper or plastics, respective sides of thefoil or strip being connected at one end to respective conductors of anelectric circuit used to operate the electric toothbrush and, inparticular, to energize the electric motor thereof, the other end of thefoil or strip being folded over and including a centrally disposedaperture onto or over which is disposed a bendable metal connector suchthat upon bending or pressing of the connector the two sides of thestrip or foil are electrically connected together to temporarily operatethe toothbrush whilst still in its packaging.

[0013] Preferably, the “try me” feature may be permanently disconnectedfrom the toothbrush after being purchased by simply being pulled awayfrom the electrical connectors to which it is attached.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention will now be described, by way of example only, withreference to the accompanying drawings in which:

[0015]FIG. 1 is a side elevation of a toothbrush according to a firstembodiment of the invention having a pair of brush heads, one of whichis angled inwardly slightly with respect to the other;

[0016]FIG. 2 is an enlarged and partly cut away view of the end of thetoothbrush of FIG. 1 which includes the brush heads;

[0017]FIG. 3 is a schematic plan view showing the mode of operation ofthe toothbrush heads of FIG. 1 and 2;

[0018]FIG. 4 is an enlarged schematic view of the brush head end of atoothbrush according to a preferred embodiment of the invention, and,

[0019]FIG. 5 is a section of elevation along the line “A”-“A” of part ofFIG. 5.

[0020]FIG. 6 is a perspective and partly cut away view of a secondembodiment of the invention, which includes a “try me” feature,

DETAILED DESCRIPTION OF THE DRAWINGS

[0021] Referring firstly to FIG. 1, an electric toothbrush showngenerally at 1 comprises a plastics body portion 2 for housing a motor,battery and associated electrical circuitry (not shown) and a detachablegenerally hollow brush head holder 3 including at the free end thereof afirst brush head 4 and a second brush head 5, each being partlyrotatable by being drivingly connected to the motor in the housing 2 ina manner to be described. A push button 6 in the housing 2 is used tooperate the toothbrush 1 and a “try me” feature shown generally at 7 canbe used to temporarily operate the toothbrush 1 in accordance with asecond embodiment of the invention in a manner to be described withreference to FIG. 6.

[0022] In FIGS. 2 and 3 there is shown the operable end of the brushhead holder 3 in which it will be seen that the first brush head 4includes a generally disc-shaped bristle holder 8 from which extendrespective sets of bristles shown generally at 9 in FIG. 2. similarly,the second brush head 5 comprises a generally disc-shaped bristle holder10 from which extend sets of bristles shown generally at 11. Brush head4 is mounted for rotation on a pivot pin 12 and brush head 5 is mountedfor rotation on a pivot pin 13, although the plane of rotation of brushhead 5 is slightly offset to the plane of rotation of brush head 4 byabout 5.degree. such that the bristles 11 are inclined slightly inwardlytowards the bristles 9. This has been found to be advantageous in thatthe brush heads 4,5 can collectively clean a greater surface area ofteeth than would be the case if both were rotatable in the same plane,by virtue of the generally curved placement of teeth within a mouth.

[0023] Reciprocating clockwise and anti-clockwise rotation of the firstbrush head 4 is facilitated by means of a bell crank mechanism whichincludes a stainless steel crankshaft 14 secured for rotation about itsmajor axis in a journal 15 extending from a spigot 16 on the inside ofthe brush head holder 3 as shown more clearly in FIG. 2. The end of thecrankshaft adjacent thereto includes an elbow joint 17, the free end ofwhich extends into a slotted region 18 within the bristle holder 8 ofthe brush head 4, which slotted region 18 is sufficiently long (or tall)to accommodate 360.degree. rotation of the crankshaft 14 and inparticular movement of the elbow 17 about the major axis of thecrankshaft 14 so that upon rotation thereof continuously clockwise oranti-clockwise it will be apparent that the brush head 4 will be forcedto oscillate back and forth about the pivot 12.

[0024] Brush head 5 is driven in a different manner by means of a drivepin 19 which extends diametrically outwardly from the bristle holder 8of the brush 4, to which it is fixed for rotation therewith, and isreceived in a slotted region 20 of the bristle holder 10 of the brushhead 5. In this case, the slotted region 20 is wide enough to permit thedrive pin 19 to move in an arc dictated by the movement of the elbow 17within the slotted region 18 about the major axis of the crankshaft 14but in an opposite sense so that clockwise movement of the brush head 4causes anticlockwise movement of the brush head 5, and vice versa.

[0025] As will be understood by those skilled in the art, the absence ofany gears in this part of the electric toothbrush 1 enables it to beeasily cleaned in running water and because there arc few moving partsas compared to toothbrushes which include gears or crank arms fordriving the or each brush head it will be appreciated that manufactureof the toothbrush according to the first embodiment of the invention canbe easily facilitated.

[0026] In FIGS. 4 and 5 there is shown a preferred embodiment of theengagement between the elbowed end 17 of the crankshaft 14 with the slot18 in the first brush head 8 and between the drive pin 19 within theslot 20 in the second brush head 10. In each case a respectivepart-spherical ball joint 21, 22 made of nylon are received within therespective slots 18, 20, which in this instance are partly arcuate so asto maximize the surface area available for contact by the ball joints21, 22. This has the advantage of minimizing wear and in practice it hasbeen found that the use of nylon in the ball joints 21, 22 givesexcellent results in terms of self-lubrication properties when the brushheads 8,10 are made of a suitable plastics material, such as PVC. Aswell, it will be apparent that during use of the toothbrush, saliva andindeed debris from foodstuffs being cleaned will also assist inlubricating the moving parts, whereafter they may be cleaned in runningwater with little risk of particles of debris adhering to the generallysmoothly profiled surfaces in this region of the toothbrush.

[0027] In FIGS. 4 and 5 the locus of movement of the ball joint 21 isshown in which it will be seen that as the crankshaft 14 rotates in onedirection only the ball joint 21 essentially assumes maximum upper andlower positions about the central axis of the crankshaft 14 within theslot 18 as shown in FIG. 5 and left to right positions as shown in FIG.4 to thereby drive the bristle holder 8 back and forth about its centralaxis in the manner shown arrowed to, in turn, drive the second bristleholder 10 via the drive shaft 14 back and forth about its own axis, butin the opposite sense so that as one brush head moves clock wise, theother always moves anti-clockwise, and so on.

[0028] In FIG. 6 there is shown a second embodiment of the inventionwhich includes a “try me” feature shown generally at 7. This includes atwin sided metal foil strip 3, such as a double sided aluminum stripseparated by a dielectric material (not shown) such as paper orplastics, respective sides of the strip 3 being electrically connectedto respective parts of a printed circuit board 24 by connectors 25 and26 forming part of a closeable circuit for operating a motor 27 to, inturn, rotate the crankshaft 14 and hence oscillate the brush heads 4, 5in the manner as described with reference to FIGS. 2 and 3.

[0029] The free end of the strip 23 has a folded over region in the formof a ring 28 onto which can be fitted a metal disc 29 which includes adomed central region 30 which may be pressed to temporarily connect bothsides of the strip 3 to complete the circuit between the connectors 25and 26 and thereby temporarily activate the toothbrush 1. As will beappreciated, because the “try me” feature 7 includes a strip 23 by whichit allows a prospective purchaser of the toothbrush to determine if andhow it works prior to purchase following pressing of the metal disc 29,after purchase the “try me” feature 7 can be effectively deactivated bysimply pulling the strip 23 away from the printed circuit board 24 andhence out of engagement with the connectors 25, 26 thereon, whereafteran end cap 31 can be refitted onto the housing 2 of the toothbrush 1 inorder to commence normal operation via pressing of the button 6.

What is claimed is:
 1. An electric toothbrush comprising, an electricmotor, a first brush head and a second brush head; said first brush headis connected by driving structure to said motor; and a drive pin extendsfrom said first brush head and is received in a guide slot within saidsecond brush head.
 2. An electric toothbrush according to claim 1wherein said electric toothbrush comprises a housing containing saidmotor and upon which housing said first and second brush heads aremounted for oscillation.
 3. An electric toothbrush according to claim 2wherein said motor drives said first brush head in an oscillatingmanner, wherein as said first brush head oscillates the drive pinextending therefrom bears against the respective sides of said guideslot to thereby drive said second head in an oscillating manner.
 4. Anelectric toothbrush according to claim 1 wherein said drive pin has afirst end secured to said first head and a second end received in saidguide slot, wherein said second end is a ball and said guide slot isformed to closely receive it therein.
 5. An electric toothbrushaccording to claim 1 wherein said first brush head is located betweensaid electric motor and said second brush head.
 6. An electrictoothbrush comprising an electric motor, a first brush head capable ofmovement, a second brush head capable of movement, a drive shaftoperatively connected to and driven by said electric motor, said driveshaft being connected to said first brush head for movably driving saidfirst brush head, a drive pin mounted at a first end of said drive pinto one of said first brush head and said second brush head and extendingtoward the other of said first brush head and said second brush head,said other of said brush head and said second brush head having a guideslot, said drive pin having a second end remote from said first end,said second end of said drive pin extending into said guide slot wherebysaid drive pin spans said first and said second brush heads without theneed for other supporting structure, said drive pin being located atsaid first brush head at a location displaced from the location of thedrive connection of said drive shaft to said first brush head, saiddrive pin being separate and distinct from said drive shaft, andmovement of said first brush head by being driven by said drive shaftbeing transmitted to said second brush head through said drive pin forjoint simultaneous movement of both said first brush head and saidsecond brush head.
 7. An electric toothbrush according to claim 6wherein said electric motor is mounted in a hollow housing at least partof said drive shaft being in said housing, said housing terminating in abrush head holder, and said first brush head and said second brush headbeing mounted in said brush head holder.
 8. An electric toothbrushaccording to claim 7 wherein each of said first brush head and saidsecond brush head is mounted on pivot structure for rotational movement.9. An electric toothbrush according to claim 8 wherein each of saidbrush heads is of disc shape, said pivot structure being a pivot pin foreach of said first brush head and said second brush head mounted to saidbrush head holder, and bristles extending outwardly from each of saidbrush heads.
 10. An electric toothbrush according to claim 6 whereinsaid first end of said drive pin is fixed to said first brush head. 11.An electric toothbrush according to claim 10 wherein said drive pin ismounted to said first brush head in a cantilevered manner.
 12. Anelectric toothbrush according to claim 10 wherein said first brush headis located between said second brush head and said motor.
 13. Anelectric toothbrush according to claim 6 wherein each of said brushheads is movably mounted for rotational oscillation in clockwise andcounterclockwise directions.
 14. An electric toothbrush according toclaim 6 wherein said second end of said drive pin terminates in a ballclosely received in said guide slot.
 15. An electric toothbrushaccording to claim 6 further comprising a third brush head, a guide slotin said third brush head and a further drive pin mounted to one of saidfirst brush head and said second brush head at one end thereof with asecond end being mounted in said guide slot of said third brush head.16. An electric toothbrush according to claim 6 wherein each of saidbrush heads is movably mounted in a rotational manner, and said drivepin being perpendicular to the axis of rotation of said first brushhead.
 17. An electric toothbrush according to claim 6 wherein each ofsaid brush heads is movable in a rotational manner, each of said brushheads having an outer surface rotatable in a plane, and said plane ofsaid second brush head being at an angle to said plane of said firstbrush head.
 18. An electric toothbrush according to claim 17 whereinsaid plane of said second brush head is inclined inwardly toward saidplane of said first brush head.
 19. An electric toothbrush according toclaim 6 wherein said first brush head and said second brush head aremounted in a brush head holder, said electric motor being mounted in ahollow housing, and said brush head holder being detachably mounted tosaid housing.
 20. A method of making and using an electric toothbrushcomprising providing a hollow housing having an electric motor thereinand a brush head holder at one end of the housing, providing two sets ofpivot structure on the brush head holder, mounting a brush head to eachof the pivot structures, operatively connecting a drive shaft to theelectric motor and to one of the brush heads, providing a drive pinwhich is separate and distinct from the drive shaft, mounting one end ofthe drive pin to one of the brush heads, disposing the drive pin fromthe one brush into a guide slot of the other brush head without anyunderlying support structure for the drive pin between the brush heads,actuating the motor to rotate the drive shaft, causing the rotatingdrive shaft to rotate the brush operatively connected to the drive shaftand to thereby cause movement of the drive pin, and using the movingdrive pin to rotate the other of the brush heads.
 21. The method ofclaim 20 wherein the drive pin is fixed to the brush head which isoperatively connected to the drive shaft and the guide slot is in theother brush head.
 22. The method of claim 20 including operativelyconnecting the drive shaft to the brush head located closer to the motorthan the other brush head.
 23. The method of claim 20 including rotatingthe brush heads in an oscillating clockwise and counterclockwisedirections.